Authorized filter servicing and replacement

ABSTRACT

A method is provided for servicing a filter, and structure is provided disabling assembly of the filter unless an authorized replacement filter element is used.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of U.S. patent application Ser. No. 11/940,626 filedNov. 15, 2007.

BACKGROUND AND SUMMARY

The invention relates to filters, servicing, and replacement, includinginternal combustion engine crankcase ventilation filters.

The invention arose during continuing development efforts directedtoward authorized service and replacement of genuine coalescer filterelements in internal combustion engine crankcase ventilation filters, toassure continuing integrity of the coalescing filter function ofseparating air and oil in the crankcase gas air-oil mixture, though thepresent system has broader application and may be used for servicingvarious filters having replaceable filter elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective assembled view of a filter for use in accordancewith the invention.

FIG. 2 is an exploded perspective view of the structure of FIG. 1.

FIG. 3 is a perspective view of a component of FIG. 2 from a differentangle.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 1.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is like FIG. 1 and shows another embodiment.

FIG. 7 is an exploded perspective view of the structure of FIG. 6.

FIG. 8 is a perspective view of a component of FIG. 7 from a differentangle.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 6.

DETAILED DESCRIPTION

FIG. 1 shows an internal combustion engine crankcase ventilation filter20 including a substantially planar low profile housing 22 having amating base 24 and cover 26 defining a coalescing filter chamber 28,FIG. 2, retaining a coalescer filter element 30 when the base and coverare mated to each other, e.g. in assembled condition by mounting bolts32. Filter element 30 and at least one of the cover and the base,preferably cover 26, have respective first and second detents 34 and 36disabling mating and mounting of base 24 and cover 26 to each other withcoalescer filter element 30 retained in coalescing filter chamber 28unless the coalescer filter element 30 has the noted first detent 34complementally interacting with the noted second detent 36.

Housing 22 has a flow path therethrough for crankcase gas from engine 40extending from a housing air-oil inlet 42 as shown at arrow 44 thenthrough coalescer filter element 30 then to a housing air outlet 46 asshown at arrow 48. The flow at inlet 42 enters an entry plenum 50 inbase 24 and then flows through openings or windows 52 in a side flange51 of the frame 53 of filter element 30 and then into upstream plenum 54between cover 26 and filter element 30 and then along an axial direction56 as shown at arrow 58, FIG. 2, into slots 60 of filter element 30 thenlaterally outwardly along lateral direction 62 as shown at arrow 64,FIG. 4, through coalescing filter media 66 into downstream plenum 68,for exit of air at housing air outlet 46, and for drainage of separatedoil at housing drain oil outlet 70. The peripheral flange of the frameof filter element 30 is sealed along diagonal gasket 72 engaged betweenbase 24 and cover 26 upon tightening of bolts 32. A pressure reliefvalve 74 may be provided at inlet or entry plenum 50 for alternate orbypass flow in the event filter element 30 clogs or otherwise becomesexcessively restrictive. Coalescer filter element 30 has an upstreamface 76, FIG. 4, receiving the air-oil mixture along the noted flowpath, and has a downstream face 78 along which separated oil coalescesand from which separated air is discharged along the noted flow path.The flow path extends axially at 58 along axial direction 56 alongupstream face 76, and then extends laterally at 64 along lateraldirection 62 from upstream face 76 to downstream face 78. The plane ofthe substantially planar low profile housing 20 lies along the notedlateral direction 62 and requires only a small space for mounting in anengine compartment. The housing is preferably mounted vertically, or atleast with drain outlet 70 at a lower downwardly disposed orientation.Coalescer filter element 30 extends along an extended lateral direction62 in a racetrack shape at coalescing filter element 66 and has a hollowinterior having a height extending along axial direction 56, and anextended longitudinal length extending along lateral direction 62 anddefining the respective longitudinal slot 60.

The noted first detent 34 is preferably provided by slot 60 of thefilter element. Second detent 36 is attached to cover 26, e.g.adhesively bonded thereto or integrally formed therewith, etc., andextends axially along axial direction 56 into slot 60. In the preferredembodiment, in addition to detent 34, additional detents are provided asshown at 80, 82, 84, each provided by a respective slot 60, and inaddition to the detent at tab 36, additional detents are provided asshown at tabs 86, 88, 90, attached to cover 26. The detents are atupstream face 76 of the coalescing filter media 66 of filter element 30and in the path of and impacted by the air-oil mixture. Detents 36, 86,88, 90 have curved arcuate surfaces in axial cross-section, for exampleas shown at 92, FIGS. 2, 3, guiding and directing air-oil mixture flowtherealong into slot 60.

Upon servicing, only an authorized replacement coalescer filter elementcan be used for internal combustion engine crankcase ventilation filter20. The replacement coalescer filter element must have one or moredetents 34, 80, 82, 84 complementally interacting with one or morerespective detents 36, 86, 88, 90 upon mating of base 24 and cover 26 toeach other. Mating of the base and cover to each other with areplacement coalescer filter element retained in coalescing filterchamber 28 is disabled unless the replacement coalescer filter elementhas the noted one or more detents 34, 80, 82, 84 complementallyinteracting with the noted one or more detents 36, 86, 88, 90 incoalescing filter chamber 28.

A method is provided for servicing internal combustion engine crankcaseventilation filter 20, including providing a substantially planar lowprofile housing 22 having a mating base 24 and cover 26 definingcoalescing filter chamber 28 retaining coalescer filter element 30 whenbase 24 and cover 26 are mated to each other. The method includesproviding the coalescer filter element 30 and at least a selected one ofthe cover and base, preferably cover 26, with respective complementalfirst and second detents 34 and 36, and disabling mating of base 24 andcover 26 to each other with coalescer filter element 30 retained incoalescing filter chamber 28 unless a coalescer filter element isselected having first detent 34 complementally interacting with seconddetent 36, and preferably with each of detents 34, 80, 82, 84complementally interacting with respective detents 36, 86, 88, 90. Firstdetent 34 is provided at one of the noted faces 76 and 78 of the filterelement, preferably upstream face 76. Second detent 36 extends proximateface 76 and interfaces with detent 34 in keyed relation. The coalescerfilter element is selected to have detent 34 complementally interactwith detent 36 by interfacing therewith in keyed relation, and likewisefor remaining detent pairs 80 and 86, 82 and 88, 84 and 90. The methodfurther includes preventing the noted mating of base 24 and cover 26 inthe absence of the noted interfacing in keyed relation of the noteddetents. The method further includes selecting the noted selected one ofthe cover and base, preferably cover 26, to have the second detent 36complementally interact with first detent 34 by interfacing therewith inkeyed relation and likewise for the remaining noted detent pairs, andpreventing the noted mating of base 24 and cover 26 in the absence ofthe noted interfacing in keyed relation of the detents. The methodfurther includes assigning a specified first detent location alongcoalescer filter element 30, and locating first detent 34 at the firstdetent location such that detent 34 has a given first detent locationrelative to coalescer filter element 30, and likewise for remainingdetents 80, 82, 84. The method further includes installing the coalescerfilter element 30 by placing the coalescer filter element in coalescingfilter chamber 28 at a specified element location therein such thatdetent 34 is located at a first detent position in coalescing filterchamber 28, and likewise for detents 80, 82, 84. The method furtherincludes assigning a specified second detent location along the selectedone of the cover and base, preferably cover 26, and locating detent 36at the noted second detent location such that detent 36 has a givensecond detent location relative to the cover 26. The method furtherincludes assembling cover 26 and base 24 in the noted mating relationsuch that detent 36 is located at a second detent position in coalescingfilter chamber 28 and such that the noted first and second detentpositions align in coalescing filter chamber 28, and the first andsecond detents 34 and 36 interface in keyed relation, and likewise forremaining detent pairs 80 and 86, 82 and 88, 84 and 90.

FIGS. 6-9 show a further embodiment. Internal combustion enginecrankcase ventilation filter 102 includes a substantially planar lowprofile housing 104 having a mating base 106 and cover 108 defining acoalescing filter chamber 110 retaining a coalescer filter element 112when the base and cover are mated to each other in assembled conditionby mounting bolts 114. Coalescer filter element 112 and at least aselected one of the cover and base, preferably cover 108, haverespective complemental first and second detents 116 and 118 disablingmating of base 106 and cover 108 to each other with coalescer filterelement 112 retained in coalescing filter chamber 110 unless thecoalescer filter element has first detent 116 complementally interactingwith second detent 118.

Housing 104 has a flow path therethrough for crankcase gas from engine120 extending from housing air-oil inlet 122 as shown at arrow 124 thenthrough coalescer filter element 112 then to housing air outlet 126 asshown at arrow 128. The flow path from inlet 122 extends through port130 in the frame 132 of filter element 112, which port 130 may includesan inertial impactor separator for pre-separation of oil from thecrankcase gas stream, which pre-separated oil may collect in well 134having an opening at the bottom thereof passing oil to a first oiloutlet drain 136 in base 106 for drainage at outlet port 138. Thecrankcase gas flow from transfer port 130, with or withoutpre-separation, passes into upstream plenum 140 between cover 108 andfilter element 112 and then passes axially downwardly in FIG. 7 alongaxial direction 142 as shown at arrow 144 into the hollow interiorspaces of the coalescing filter media of the filter element at slots 146and then laterally along lateral direction 148 as shown at arrow 150,FIG. 9, through the coalescing filter media 152 to downstream plenum 154for exit of air at air outlet 126 as shown at arrow 128, and exit ofcoalesced oil at oil outlet 156. The outer peripheral flange of theframe of filter element 112 is sealed at diagonally extending gasket 158engaged between cover 108 and base 106. Housing 104 sits generallyhorizontally in the engine compartment, e.g. on top of a cylinder head,or at a given angle with drains 138, 156 preferably at a lower locationpointing at least partially downwardly. Coalescing filter media 152 offilter element 112 has an upstream face 160 receiving the air-oilmixture along the noted flow path, and has a downstream face 162 alongwhich separated oil coalesces and from which separated air is dischargedalong the noted flow path. The flow path extends axially as shown atarrow 144 along axial direction 142 along upstream face 160 of thefilter media, and then extends laterally as shown at arrow 150 alonglateral direction 148 from upstream face 160 to downstream face 162. Theplane of substantially planar low profile housing 104 lies along lateraldirection 148. Coalescer filter element 112 at filter media 152 extendsalong an extended lateral direction 164 in a racetrack shape having oneor more hollow interiors 146 each having a height extending along axialdirection 142, and an extended longitudinal length extending alonglateral direction 164 and defining the respective slot 146.

First detent 116 is provided by the noted slot 146. Second detent 118 isprovided by a tab attached to the noted selected one of the cover andbase, preferably cover 106, e.g. adhesively bonded thereto or integrallyformed therewith, etc., and extending axially into slot 146. In thepreferred embodiment, filter element 112 has the noted detent 116 andadditionally has further detents 166, 168, 170 provided by respectiveslots. Further in the preferred embodiment, cover 106 has detent 118provided by the noted tab attached thereto and additionally has detenttabs 172, 174, 176 attached thereto, and extending axially intorespective slots providing respective detents 116, 166, 168, 170.Detents 116 and 118 are at upstream face 160 of the coalescing filtermedia 152 of the filter element and in the path of and impacted by theair-oil mixture, as are respective detent pairs 166 and 172, 168 and174, 170 and 176. Detent 118 has a curved arcuate surface in axialcross-section guiding and directing air-oil mixture therealong into slot146. The remaining detents provided by the respective tabs 172, 174, 176are comparable.

In the embodiment of FIGS. 6-9, in addition to the noted first andsecond detents 116 and 118, a third detent 180 on coalescer filterelement 112 is laterally spaced from first detent 116 and also laterallyspaced from each of the noted upstream and downstream faces 160 and 162of coalescing filter media 152 of the filter element. A fourth detent182 is provided on a given one of the cover and base, preferably cover108, and is laterally spaced from second detent 118 and complementallyinteracts with third detent 180 upon mating of cover 108 and base 106 inassembled condition by mounting bolts 114. First detent 116, seconddetent 118, third detent 180, and fourth detent 182 prevent mating ofbase 106 and cover 108 to each other with coalescer filter element 112retained in coalescing filter chamber 110 unless the coalescer filterelement has both: a) the first detent 116 complementally interactingwith second detent 118 extending axially thereinto; and b) third detent180 complementally interacting with fourth detent 182.

The noted fourth detent 182, FIGS. 7, 8, is preferably provided by anaxially extending tab attached to cover 108, e.g. adhesively bondedthereto or integrally formed therewith, etc. The noted third detent 180is preferably provided by a retaining wall forming well 134 andreceiving tab 182 extending axially therealong. Tab 182 has an L-shapein lateral cross-section, the L-shape having first and second legs 184and 186. The noted retaining wall at 180 is provided by a corner segment188 of the well 134 having first and second wall sections 190 and 192meeting at a junction at 188 and complementally receiving at least oneof the noted legs 184 and 186. In the preferred embodiment, legs 184 and186 meet at a joint 194 extending axially therealong along axialdirection 142. First leg 184 extends axially along first wall section190. Second leg 186 extends axially along second wall section 192.Junction 188 receives joint 194 extending axially therealong.

For servicing, an authorized replacement coalescer filter element 112must be used for the internal combustion engine crankcase ventilationfilter 102. The replacement coalescer filter element must have firstdetent 116 complementally interacting with second detent 118 upon matingof base 106 and cover 108 to each other. The system disables the notedmating of base 106 and cover 108 to each other with replacementcoalescer filter element 112 retained in coalescing filter chamber 110unless the replacement coalescer filter element has the noted firstdetent 116 complementally interacting with the noted second detent 118in the coalescing filter chamber. In the preferred embodiment, otherdetent pair conditions must be met, namely other detent pairs must alsocomplementally interact with each other, namely detent pairs 166 and172, 168 and 174, 170 and 176, 180 and 182.

A method is provided for servicing internal combustion engine crankcaseventilation filter 102, including providing a substantially planar lowprofile housing 104 having a mating base 106 and cover 108 defining acoalescing filter chamber 110 retaining a coalescer filter element 112when the base and cover are mated to each other in assembled conditionby mounting bolts 114. The method includes providing the coalescerfilter element 112 and at least one of the cover and base, preferablycover 108, with respective complemental first and second detents 116 and118, and disabling mating of base 106 and cover 108 to each other withcoalescer filter element 112 retained in coalescing filter chamber 110unless a coalescer filter element is selected having first detent 116complementally interacting with second detent 118. The method includesselecting the coalescer filter element to have first detent 116complementally interact with second detent 118 by interfacing therewithin keyed relation. The method includes preventing the mating of base 106and cover 108 in the absence of the noted interfacing in keyed relationof the first and second detents 116 and 118. The method includesselecting the noted selected one of the cover and base, preferably cover108, to have the noted second detent 118 complementally interact withthe first detent 116 by interfacing therewith in keyed relation. Themethod includes preventing the noted mating of base 106 and cover 108 inthe absence of the noted interfacing in keyed relation of detents 116and 118. In the preferred embodiment, the method includes providing athird detent such as 180 on the coalescer filter element 112, andproviding a fourth detent such as 182 on a given one of the cover andbase, preferably cover 108. In such embodiment, the method includesdisabling the mating of base 106 and cover 108 to each other with thecoalescer filter element 112 retained in coalescing filter chamber 110unless a coalescer filter element is selected having both: a) the firstdetent 116 complementally interacting with the second detent 118; and b)the third detent 180 complementally interacting with the fourth detent182. The method includes assigning a specified first detent locationalong coalescer filter element 112, and locating the first detent 116 atthe first detent location such that the first detent 116 has a givenfirst detent location relative to coalescer filter element 112. Themethod includes installing coalescer filter element 112 by placing thecoalescer filter element in the coalescing filter chamber 110 at aspecified element location therein such that the first detent 116 islocated at a first detent position in coalescing filter chamber 110. Themethod includes assigning a specified second detent location along thenoted selected one of the cover and base, preferably cover 108, andlocating the second detent 118 at the second detent location such thatthe second detent 118 has a given second detent location relative tocover 108. The method includes assembling cover 106 and base 108 inmating relation such that the second detent 118 is located at the notedsecond detent position in coalescing filter chamber 110 and such thatthe noted first and second detent positions align in coalescing filterchamber 110, and the first and second detents 116 and 118 interface inkeyed relation.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. The different configurations, systems, and method stepsdescribed herein may be used alone or in combination with otherconfigurations, systems and method steps. It is to be expected thatvarious equivalents, alternatives and modifications are possible withinthe scope of the appended claims. The structure and methodology hereinmay be used beyond internal combustion engine crankcase ventilationfilter applications to other filter applications and servicing andreplacement filter elements therefor. Other embodiments are envisionedthat may include other possible features, such as complementallyinteracting protuberances, keyed interlocking fingers, male-femaleconnections, plastic pegs, prongs, hooks, clamping structures,integrated interlocking edges, and other structural devices whichreceivably interact with one another, as well as other structuresproviding the functions herein or functional equivalents thereof.

What is claimed is:
 1. An internal combustion engine crankcase ventilation filter comprising a substantially planar low profile housing having a mating base and cover defining a coalescing filter chamber retaining a coalescer filter element when said base and said cover are mated to each other, said coalescer filter element and at least a selected one of said cover and said base having respective complemental first and second detents disabling mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless said coalescer filter element has said first detent complementally interacting with said second detent, said housing having a flow path therethrough for crankcase gas from said engine, said flow path extending from a housing air-oil inlet then through said coalescer filter element then to a housing air outlet said coalescer filter element having an upstream face receiving an air-oil mixture along said flow path, and a downstream face along which said separated oil coalesces and from which said separated air is discharged along said flow path, said first detent is at one of said faces, said second detent extends proximate said one face and interfaces with said first detent in keyed relation, said second detent including a directional guide surface guiding and directing flow therealong and also turning the flow from a first flow direction to a second flow direction.
 2. The internal combustion engine crankcase ventilation filter according to claim 1 wherein: said flow path extends axially along an axial direction along said upstream face, and extends laterally along a lateral direction from said upstream face to said downstream face; the plane of said substantially planar low profile housing lies along said lateral direction; said coalescer filter element extends along an extended lateral direction in a racetrack shape having a hollow interior having a height extending along said axial direction and an extended longitudinal length extending along said lateral direction and defining a longitudinal slot; said first detent comprises said slot; and said second detent extends axially into said slot.
 3. The internal combustion engine crankcase ventilation filter according to claim 2 wherein said first and second detents are at said upstream face and in the path of and impacted by said air-oil mixture.
 4. The internal combustion engine crankcase ventilation filter according to claim 2 comprising: a third detent on said coalescer filter element and laterally spaced from said first detent at said slot and also laterally spaced from each of said upstream and downstream faces; a fourth detent on a given one of said cover and said base and laterally spaced from said second detent and complementally interacting with said third detent upon mating of said cover and said base; wherein said first, second, third, and fourth detents prevent mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless said coalescer filter element has both: a) said first detent at said slot complementally interacting with said second detent extending axially thereinto; and b) said third detent complementally interacting with said fourth detent.
 5. The internal combustion engine crankcase ventilation filter according to claim 2 wherein said second detent has a curved arcuate surface in axial cross-section guiding and directing air-oil mixture flow therealong into said slot.
 6. The internal combustion engine crankcase ventilation filter according to claim 4 wherein said fourth detent comprises an axially extending tab, and said third detent comprises a retaining wall receiving said tab extending axially therealong.
 7. The internal combustion engine crankcase ventilation filter according to claim 6 wherein: said tab has an L-shape in lateral cross-section, said L-shape having first and second legs; and said retaining wall comprises a corner segment having first and second wall sections meeting at a junction and complementally receiving at least one of said legs.
 8. The internal combustion engine crankcase ventilation filter according to claim 7 wherein: said first and second legs meet at a joint; said junction receives said joint extending axially therealong; said first leg extends axially along said first wall section; and said second leg extends axially along said second wall section.
 9. A replacement coalescer filter element for the internal combustion engine crankcase ventilation filter according to claim 1 wherein said replacement coalescer filter element has said first detent complementally interacting with said second detent upon mating of said base and said cover to each other and disables said mating of said base and said cover to each other with said replacement coalescer filter element retained in said coalescing filter chamber unless said replacement coalescer filter element has said first detent complementally interacting with said second detent in said coalescing filter chamber.
 10. The replacement filter element according to claim 9 wherein: said housing has a flow path therethrough for crankcase gas from said engine, said flow path extending from a housing air-oil inlet then through said coalescer filter element then to a housing air outlet; said coalescer filter element has an upstream face receiving an air-oil mixture along said flow path, and a downstream face along which separated oil coalesces and from which separated air is discharged along said flow path; said flow path extends axially along an axial direction along said upstream face, and extends laterally along a lateral direction from said upstream face to said downstream face; the plane of said substantially planar low profile housing lies along said lateral direction; said coalescer filter element extends along an extended lateral direction in a racetrack shape having a hollow interior having a height extending along said axial direction and an extended longitudinal length extending along said lateral direction and defining a longitudinal slot; said first detent comprises said slot; and said second detent extends axially into said slot.
 11. The internal combustion engine crankcase ventilation filter according to claim 1 wherein said second flow direction is along said upstream face.
 12. The internal combustion engine crankcase ventilation filter according to claim 11 wherein said flow path extends along a first sequential direction to said second detent and then extends along a second sequential direction axially along an axial direction along said upstream face and then extends along a third sequential direction laterally along a lateral direction through said coalescing filter element from said upstream face to said downstream face.
 13. The internal combustion engine crankcase ventilation filter according to claim 12 wherein said first sequential direction extends laterally and is parallel to said third sequential direction, and said directional guide surface of said second detent turns said flow from said first sequential direction to said second sequential direction.
 14. The internal combustion engine crankcase ventilation filter according to claim 13 wherein said directional guide surface of said second detent is curved along a curved arcuate surface in axial cross-section.
 15. An internal combustion engine crankcase ventilation filter comprising a substantially planar low profile housing having a mating base and cover defining a coalescing filter chamber retaining a coalescer filter element when said base and said cover are mated to each other, said coalescer filter element and at least a selected one of said cover and said base having respective complemental first and second detents disabling mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless said coalescer filter element has said first detent complementally interacting with said second detent, said housing having a flow path therethrough for crankcase gas from said engine, said flow path extending from a housing air-oil inlet then through said coalescer filter element then to a housing air outlet, said coalescer filter element having an upstream face receiving an air-oil mixture along said flow path, and a downstream face along which said separated oil coalesces and from which said separated air is discharged along said flow path, wherein said second detent is at said upstream face and interfaces with said first detent in keyed relation.
 16. The internal combustion engine crankcase ventilation filter according to claim 15 wherein said second detent includes a directional guide surface guiding and directing flow therealong and also turning the flow from a first flow direction to a second flow direction, wherein said second flow direction is along said upstream face.
 17. An internal combustion engine crankcase ventilation filter comprising a substantially planar low profile housing having a mating base and cover defining a coalescing filter chamber retaining a coalescer filter element when said base and said cover are mated to each other, said coalescer filter element and at least a selected one of said cover and said base having respective complemental first and second detents disabling mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless said coalescer filter element has said first detent complementally interacting with said second detent, said housing having a flow path therethrough for crankcase gas from said engine, said flow path extending from a housing air-oil inlet then through said coalescer filter element then to a housing air outlet, said coalescer filter element having an upstream face receiving an air-oil mixture along said flow path, and a downstream face along which said separated oil coalesces and from which said separated air is discharged along said flow path, wherein said coalescer filter element is a closed-loop defining a hollow interior, and said second detent is at said hollow interior and interfaces with said first detent in keyed relation.
 18. The internal combustion engine crankcase ventilation filter according to claim 17 wherein said second detent includes a directional guide surface guiding and directing flow therealong and also turning the flow from a first flow direction to a second flow direction, wherein one of said directions is along said hollow interior.
 19. An internal combustion engine crankcase ventilation filter comprising a substantially planar low profile housing having a mating base and cover defining a coalescing filter chamber retaining a coalescer filter element when said base and said cover are mated to each other, said coalescer filter element and at least a selected one of said cover and said base having respective complemental first and second detents disabling mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless said coalescer filter element has said first detent complementally interacting with said second detent, said housing having a flow path therethrough for crankcase gas from said engine, said flow path extending from a housing air-oil inlet then through said coalescer filter element then to a housing air outlet, said coalescer filter element having an upstream face receiving an air-oil mixture along said flow path, and a downstream face along which separated oil coalesces and from which said separated air is discharged along said flow path, wherein said coalescer filter element extends along an extended lateral direction in a racetrack shape having a hollow interior having a height extending along an axial direction and an extended longitudinal length extending along said lateral direction and defining a longitudinal slot hollow interior, wherein said second detent extends into said longitudinal slot hollow interior.
 20. The internal combustion engine crankcase ventilation filter according to claim 19 wherein said second detent includes a directional guide surface guiding and directing flow therealong and also turning the flow from a first flow direction to a second flow direction, wherein one of said flow directions is along said axial direction in said longitudinal slot hollow interior, and the other of said flow directions is along said lateral direction adjacent said longitudinal slot hollow interior. 